Hi, I'm New to hacker news, but I also built an android app on the side and have 20ish downloads. I built it all myself and it cost only a couple hundred dollars. However I can't get users to stay. Most of the 20ish users installed it and then didn't play. So my question is what is your plan to get users to download and keep them interested? My app took about 4 months and I build it using Xamarin.Android. I don't want to break any forum rules by adding a link to my app, but I would be interested in getting some direction for marketing and feedback.
It's hard to tell with only 20 downloads. Some people will just download it and not use it, it just happens sometimes. Is it a free app or paid for? If it's free then this will happen more often. I'd suggest finding out where they stop, is there a signup screen that stops them or is it something to do with the setup? I imagine you don't have any information for them if no one has started playing it, but if you do, contact them and ask why they stopped. Be friendly to them about it, people will help you out.
Good luck. It's hard, but it can be a rolling ball, getting a few people playing can help things take off slowly.